So, this is Leopard, and these are my off-the-cuff reactions.
Time Machine
Great idea, but my goodness, Apple’s designers must’ve been overdoing the weed. That is the cheesiest interface I’ve seen in a long time.
Spaces
Everyone is going to say it. Virtue Desktops
iCal
I was really hoping for a new non-metal interface, but alas. The new collaboration features make up for that though, this is something I’ve been wanting.
More for me to get excited about here. I already use Mail to keep notes to myself (as drafts), but the todos feature looks great. Initially I’d missed that Mail was getting support for RSS feeds too. Many will hate this idea, but it suits the way I use RSS, so I’m keen to see this in action.
iChat
Unified interface! Yes! Screen sharing! Yes!! Fun wacky backgrounds and effects!! Oh, if you must.
Voice over
The new synthesised voice sounds amazing, but I would like one that sounds like my wife’s scottish tones.
There are more new features to come apparently. Generally, I was hoping for more advancement in unifying the interface, as well as new hotness in Safari, but maybe that can still happen. Like Tiger, a lot of Leopard’s strengths seem to be in the underlying technologies like 64bit applications and core animation.